Apparatus and method for transmitting multimedia data in a broadcast system

ABSTRACT

An apparatus and a method for transmitting multimedia data in a broadcast system are provided. A method for constructing a payload for a multimedia frame to be transmitted via a heterogeneous network, in a broadcast system that supports an Internet protocol-based multimedia service, includes dividing the data so as to transmit data of at least one media type and constructing a data region based on each datum of the divided data, constructing a header region including information on the state of the data contained in the data region and/or information on the data region, and combining the data region and the header region to construct a payload for the multimedia frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of prior application Ser.No. 13/980,462, filed on Jul. 18, 2013, which was based on NationalStage application under 35 U.S.C. § 371 of an International applicationfiled on Jan. 19, 2012 and assigned application PCT/KR2012/000468, andclaims the benefit under 35 U.S.C. § 365(b) of a Korean patentapplication filed on Jan. 19, 2011 in the Korean Intellectual PropertyOffice and assigned Serial No. 10-2011-0005654, the entire disclosure ofeach of which is hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure relates to an apparatus and method fortransmitting multimedia data in a broadcast system. More particularly,the present disclosure relates to an apparatus and method fortransmitting multimedia data via a heterogeneous network in a broadcastsystem that supports an Internet-protocol-based multimedia service.

BACKGROUND

A broadcast network of the related art generally uses a Moving PictureExperts Group-2 Transport Stream (MPEG-2 TS) for transmission ofmultimedia contents. That is, the MPEG-2 TS is used as a representativetransmission technique for transmitting a bitstream in which a pluralityof broadcast programs (a number of encoded video bit streams) aremultiplexed in an erroneous transmission environment. For example, theMPEG-2 TS is suitable for use in digital TV broadcasting of themultimedia era.

FIG. 1 illustrates a hierarchical structure for supporting the MPEG-2 TSaccording to the related art.

Referring to FIG. 1, layers for supporting the MPEG-2 TS include a mediacoding layer (MEDIA CODING LAYER) 110, a synchronization layer (SYNCLAYER) 120, a delivery layer (DELIVERY LAYER) 130, a network layer(NETWORK LAYER) 140, data link layer (DATA LINK LAYER) 150, and aphysical layer (PHYSICAL LAYER) 160.

The media coding layer (MEDIA CODING LAYER) 110 and the synchronizationlayer (SYNC LAYER) 120 are constructed in a format that facilitates useof media data as the basic unit of recording or transmission. Thedelivery layer (DELIVERY LAYER) 130, the network layer (NETWORK LAYER)140, the data link layer (DATA LINK LAYER) 150, and the physical layer(PHYSICAL LAYER) 160 construct a multimedia frame for recording of adata block in a format constructed by the synchronization layer (SYNCLAYER) 120 in a separate recording medium or for transmission of thedata block. The constructed multimedia frame is transmitted to asubscriber terminal through a predetermined network. To this end, thesynchronization layer (SYNC LAYER) 120 is constructed by a fragmentationblock (FRAGMENT BLOCK) 122 and an access unit (ACCESS UNIT) 124, and thedelivery layer (DELIVERY LAYER) 130 is constructed by an MPEG-2 TS/MP4RTP Payload Format/Flute 132, an RTP/HTTP 134, and an UDP/TCP 136.

However, the MPEG-2 TS has several limitations in supporting multimediaservices. The limitations of the MPEG-2 TS is one-way communication,inefficiency in transmission due to a fixed frame size, a specializedtransmission protocol for audio/video, and a generation of unnecessaryoverhead in a transmission using Internet Protocols (IPs).

Thus, in order to overcome the limitations of the MPEG-2 TS, the MPEGMEDIA Transport (MMT) standard is newly suggested as one of multimediatransmission techniques for supporting multimedia services based on theMPEG technology. For example, the MMT standard may be applied toefficiently transmit hybrid contents through a heterogeneous network.Herein, the hybrid contents denote a set of contents having multimediaelements based on video/audio/application. The heterogeneous networkdenotes networks in which a broadcast network and a communicationnetwork coexist.

The MMT standard aims at defining a more friendly transmission techniquefor the IP that is a basic technique in a transmission network for themultimedia services. Hence, the MMT standard is intended to provide anefficient MPEG transmission technique in a multimedia serviceenvironment that changes based on the IP, and is steadily studied andstandardized. In particular, for the MMT standard in a recent multimediaservice environment that provides a hybrid network and hybrid contents,a need exists for a plan for providing an efficient MPEG transmissiontechnique.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present disclosure.

SUMMARY

Aspects of the present disclosure are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentdisclosure is to provide a method for transmitting multimedia datathrough a heterogeneous network in a broadcast system that supports anInternet-protocol-based multimedia service.

Another aspect of the present disclosure is to provide a method andapparatus for transmitting multimedia data by constructing a payload ofa multimedia frame to provide hybrid content or a hybrid service basedon the MMT technology.

Another aspect of the present disclosure is to provide a method andapparatus for constructing a header region and a data region of an MMTaccess unit to construct a payload of a multimedia frame for providinghybrid content or a hybrid service based on the MMT technology.

In accordance with an aspect of the present disclosure, a method forconstructing a payload of a multimedia frame to be transmitted via aheterogeneous network in a broadcast system that supports anInternet-protocol-based multimedia service is provided. The methodincludes dividing data so as to transmit data of at least one media typeand constructing a data region based on the divided data, constructing aheader region including at least one of information on the state of thedata included in the data region and/or information on the data region,and combining the data region and the header region to construct apayload for the multimedia frame.

In accordance with another aspect of the present disclosure, anapparatus for constructing a payload of a multimedia frame to betransmitted via a heterogeneous network in a broadcast system thatsupports an Internet-protocol-based multimedia service is provided. Theapparatus includes a data region construction unit for dividing data soas to transmit data of at least one media type and constructing a dataregion based on the divided data, a header region construction unit forconstructing a header region including at least one of information onthe state of the data included in the data region and/or information onthe data region, and a payload construction unit for combining the dataregion and the header region to construct a payload for the multimediaframe.

The present disclosure may support efficient MPEG transmission in amultimedia environment by providing a hybrid service or content via aheterogeneous network.

The present disclosure may also provide high-quality content, hybridcontent, and a heterogeneous network.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 illustrates a conventional hierarchical structure for supportinga Moving Picture Experts Group-2 Transport Stream (MPEG-2 TS) accordingto the related art;

FIG. 2 illustrates a concept of an MPEG MEDIA Transport (MMT) service bya broadcast system based on the MMT standard according to an embodimentof the present disclosure;

FIG. 3 illustrates a hierarchical structure of layers for transmittingmultimedia data corresponding to multi-service/content via aheterogeneous network in an MMT system according to an embodiment of thepresent disclosure; and

FIG. 4 is a flowchart for constructing a payload of a multimedia framecorresponding to a multi-service/content and transmitting the payload ofthe multimedia frame over a heterogeneous network in an MMT systemaccording to an embodiment of the present disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiment of the present disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thepresent disclosure. In addition, descriptions of well-known functionsand constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of the presentdisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of the presentdisclosure is provided for illustration purpose only and not for thepurpose of limiting the present disclosure as defined by the appendedclaims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

FIG. 2 illustrates a concept of an MPEG MEDIA Transport (MMT) service bya broadcast system based on the MMT standard according to an embodimentof the present disclosure. Hereinafter, the MMT standard will bereferred to as an ‘MMT’ system.

Referring to FIG. 2, contents for the MMT service may include Ultra HighDefinition (UHD), Video On Demand (VOD), live streaming, files, widgets,E-books, and metadata. However, the content for the MMT service mayinclude any content that may be expressed in an electric signal.

To construct a multimedia frame, multimedia data corresponding to eachof various contents are encapsulated in a predetermined format by an MMTEncapsulator (ME), and the multimedia frame is transmitted to asubscriber terminal via a hybrid delivery over a heterogeneous network.The heterogeneous network denotes a network having a transmissionenvironment where a broadcast network and an IP network coexist. Themultimedia frame is a transport frame for the MMT service, and is apacket of an MMT access unit.

The subscriber terminal (adaptation) having received the multimediaframe transmitted in the hybrid delivery through the heterogeneousnetwork extracts multimedia data corresponding to desired content fromthe multimedia frame, and provides a video/audio/application to a userbased on the extracted multimedia data. Each multimedia datacorresponding to the video/audio/application provided for a specificcontent is defined as an ‘MMT asset’. The subscriber terminal mayinclude any terminal that can support a multimedia service. Arepresentative example of the subscriber terminal may include an IP TVor a smart phone.

FIG. 3 illustrates a hierarchical structure of layers for transmittingmultimedia data corresponding to multi-service/content over aheterogeneous network in an MMT system according to an embodiment of thepresent disclosure.

Referring to FIG. 3, seven layers are required for transmitting aconstructed multimedia frame. The seven layers include a media codinglayer (MEDIA CODING LAYER) 310, an encapsulation layer (ENCAPSULATIONLAYER, hereinafter, referred to as a “Layer E”) 320, a delivery layer(DELIVERY LAYER, hereinafter, referred to as a “Layer D” or a “Layer T”)330 or 390, a network layer (NETWORK LAYER) 340, a data link layer (DATALINK LAYER) 350, a physical layer (PHYSICAL LAYER) 360, and a controllayer (CONTROL LAYER, hereinafter, referred to as a “Layer C”) 370 and380.

According to an embodiment of the present disclosure, multimedia dataaccording to a multi-content or a multi-service is generated by themedia coding layer (MEDIA CODING LAYER) 310 and the Layer E 320, so thatthe two layers may be considered as elements of a “multimedia datageneration part”. A multimedia frame is constructed by the Layer D 330,so that the Layer D 300 may be considered as an element of a “multimediaframe construction part”. The Layer D 330 included in the multimediaframe construction part includes header information containing a frameidentifier and information required for measuring a quality of aconnection service between network layers and end-to-end networkcapabilities, and constructs a multimedia frame by combining the headerinformation and multimedia data.

Technology areas corresponding to three layers among the seven layersare important for the MMT standard. The three technology areascorrespond to the Layer E 320, the Layer D 330 and 390, and the Layer C370 and 380, respectively. The Layer E 320 plays a role of generatinghybrid content, the Layer D 330 and 390 plays a role of efficientlytransmitting the generated content through a heterogeneous network, andthe Layer C 370 and 380 plays a role for general control in consumptionmanagement and transmission management of the hybrid content.

The Layer E 320 includes an MMT E.3 layer 322, an MMT E.2 layer 324, andan MMT E.1 layer 326. The MMT E.3 layer 322 receives an input of codedmultimedia data provided from the media coding layer 310 and generates adata fragment which is the basic unit for the MMT service. The MMT E.2layer 324 generates an Access Unit (AU) for the MMT service based on thedata fragment generated by the MMT E.3 layer 322. The MMT E.1 layer 326generates a format for generation, storage, and transmission of thehybrid content through a combination or a division of the AUs providedby the MMT E.2 layer 324. The MMT E.1 layer 326 transmits MMT assetinformation to the MMT C.1 layer 370 to help the MMT C.1 layer 370 setan AU, and transmits ME information to the MMT C.1 layer 370 toguarantee Quality of Service (QoS) of the ME.

The Layer D 330 and 390 includes an MMT D.1 layer 332, an MMT D.2 layer334, and an MMT D.3 layer 390. The MMT D.1 layer 332 corresponds to anApplication Protocol (AP) performing a similar role as the Real-timeTransfer Protocol (RTP) or the HyperText Transfer Protocol (HTTP). TheMMT D.2 layer 334 corresponds to a network layer protocol performing asimilar role as the User Datagram Protocol (UDP) or the TransmissionControl Protocol (TCP). The MMT D.3 layer 390 performs an operation foran optimization between respective layers included in the Layer E 320and respective layers included in the Layer D 330.

The Layer C 370 and 380 includes an MMT C.1 layer 370 and a MMT C.2layer 380. The MMT C.1 layer 370 provides information on generation andconsumption of hybrid content and the MMT C.2 layer 380 providesinformation on transmission of the hybrid content. The MMT C.1 layer 370transmits service discovery information required for guaranteeing theQoS of the ME to the MMT D1 layer 332. The service discovery informationincludes application layer Forward Error Correction (FEC) and sessiondescription such as security information. The MMT C.1 layer 370 alsorequests delivery of the ME from the MMT D1 layer 332.

In the present disclosure, to transmit the ME in the Layer D 330 and390, the ME may include AUs that are basic units of the Layer D 330 and390. Each AU may be split into multiple fragments and according to asize, several AUs may be aggregated to form a multimedia frame fortransmission.

In the Layer D 330 and 390, the ME is transmitted using an MMT AccessUnit (MAU). The MAU is the smallest data entity for transmission andforms a payload of a multimedia frame. The MAU is significantlyefficient and simple as the AU, and the ME may be split into two or morefragments in the MAU. The MAU permits interleaving for transmission asan option.

An MAU transmits an ME at a possible bit rate and to transmit aparticular ME, a minimum configuration is required. To allow simpledesigning, specific modes may be considered for transmission of MEsexcept for a dedicated receiver, and for example, MMT streams modes maybe considered as well as a generic mode available for transmission of aparticular MMT stream. In addition, for future transmission ofinformation associated with an additional system, an auxiliary field maybe constructed to transmit any data.

Most Internet Protocol (IP) networks have quite small MaximumTransmission Unit (MTU) sizes. Thus, a payload format of a frame permitsfragmentation of an MAU, and one MAU may be fragmented for transmissionthrough a payload of a multimedia frame. As a result of thefragmentation, if the multimedia frame is lost during transmission, anMAU fragment, instead of the entire MAU, may be lost.

In the MMT system, for simplification of operations of receivers, amultimedia frame may carry one or two or more complete MAUs or a singlefragment of one MAU. In case of live streaming or Video On Demand (VOD)transmission, an MAU may be fragmented into a same size, and for filetransmission, an MAU may be fragmented into an arbitrary size.

When a multimedia frame carries adjacent sequences between MAUs, theuser may regard a loss of the multimedia frame as a decoding gap.Therefore, it is preferable but not necessary to allow access units tobe interleaved in RTP packets, and for usual cost and executioncomplexity in latency, great error resiliency may be achieved withrespect to a packet loss.

One MAU may transmit multiple AUs. The AUs may have a variable size aswell as a fixed size in octets. To parse variously concatenated AUs inone multimedia frame, the size of each AU is known to a receiver. Inconcatenation for a constant AU size, this size is transmittedout-of-band through a Multipurpose Internet Mail Extensions (MIME)format parameter. In concatenation for variable size AUs, an MAUtransmits each AU size in-band.

When multiple AUs are carried in one multimedia frame to simplifyoperations of receivers in the MMT system, a number of each AU needs tobe included in the multimedia frame. Also, for selective interleaving ofan AU, a payload format of the multimedia frame includes indexinformation transmitted to the AU. In the MMT system, a server providesreceivers with information regarding a buffer resource for allocationfor de-interleaving, and then selects an interleaving pattern freelywithout transmitting the information prior to the receivers, thusdynamically adopting an interleaving pattern based on an AU size and anerror rate.

As such, an MAU is usefully used in the MMT system, and herein below,the MAU will be described in detail.

First, as for a structure of the MAU, the MAU includes an MAU header ina header region and an MMT payload in a data region as shown in Table 1.The MAU header includes information about data of the MMT payload, andthe MMT payload includes an AU of an ME. Table 1 below shows a structureof the MAU.

TABLE 1 MAU Header MMT Payload

Table 2 below shows the information included in the MAU header.

TABLE 2 bits 0-15 16-31 0 packetType sourceportNumber 32destinationportNumber length 64 numberofItems sequenceNumber 96Timestamp Indicator of MAU

Table 2 shows an example of a 127 bit MAU header. The informationincluded in the MAU header composed of 127 bits, includes various fieldsand each field indicates particular information by using 15 bits. Afirst field (0^(th) through 15^(th) bits) indicates a packet type(packetType), a second field (16^(th) through 31^(st) bits) indicates asource port number (sourceportNumber), a third field (32^(nd) through47^(th) bits) indicates a destination port number(destinationportNumber), a fourth field (48^(th) through 63^(rd) bits)indicates length (length), a fifth field (64^(th) through 79^(th) bits)indicates a number of items (numberofItems), a sixth field (80^(th)through 95^(th) bits) indicates a sequence number (sequenceNumber), aseventh field (96^(th) through 111^(th) bits) indicates a timestamp(Timestamp), and an eighth field (112^(th) through 127^(th) bits)indicates an indicator of an MAU. Hereinafter, detailed contentsindicated by the foregoing information will be described.

A field indicating a packet type indicates a state of data included inthe MMT payload. That is, when an ME is divided into a plurality ofblocks and each block is transmitted using an MAU, the field indicateswhether one block is completely included in the MMT payload, whether theblock is divided and thus some of the block is included in the MMTpayload, or whether a plurality of blocks are included.

The packet type includes a Type of an MAU (TM) and Fragment Information(FI). The TM indicates the type of the MAU by using one bit, andindicates a type of a payload, such as transmission type or controltype. If the TM is set to 1, the TM indicates that the MAU includes anMMT control message. The FI indicates information about a fragmentincluded in the MMT payload by using 2 bits. That is, if a block of theME is fragmented and included in the MMT payload, the FI indicatesinformation about the fragment. For example, the FI may be indicated asshown in Table 3.

TABLE 3 FI Fragment State 00 No Fragment 01 First Fragment 10 OtherFragment than First Fragment and Last Fragment 11 Last Fragment

In Table 3, (00) indicates that a fragment of a block of the ME is notincluded in the MMT payload and a complete block is included in the MMTpayload. (01) indicates that the first fragment of the ME is included inthe MMT payload, (10) indicates that a fragment other than the firstfragment and the last fragment among fragments of the block of the MEare included in the MMT payload, and (11) indicates that the lastfragment of the block of the ME is included in the MMT payload.

A field regarding a source port number indicates a port of atransmitter, and in a specific case, a port for response is assumed. Ifa field corresponding to the source port number is not used, the numberis 0. If a source host is a client, the port number is a temporary portnumber, and if the source host is a server, the port number is awell-known port number.

A field regarding a destination port number indicates a port of areceiver. If the client is a destination host, the port number is atemporary port number like the source port number, and if thedestination host is a server, the port number is a well-known portnumber.

A field regarding a length indicates a length of a payload (a header anddata). The minimum length is a length of the header and thus is 8 bytes.The size of the field indicating the length is theoretically limited to65535 bytes (8-byte header+65,527-byte data). An actual limitation of adata length forced by the basic Ipv4 protocol is 65,507 bytes(65,487-byte MAU header, 20-byte IP header).

A field regarding the number of items indicates related information whenany one block of an ME is included in an MMT payload or a plurality ofblocks are aggregated.

For example, if the ME is divided into a plurality of blocks, any one ofwhich is included in the MMT payload, then the field indicates the orderof the block included in the MMT payload or a number of remainingblocks. If a plurality of blocks are aggregated, the field indicates thenumber of blocks. In this case, each of the plurality of blocks may berelated with media data of a different type. The semantic of the fieldregarding the number of items depends on a frame type.

A field regarding a sequence number increases one by one for each MAUand is transmitted, and is used in the receiver to detect an MAU loss.The MMT system does not perform any operation with respect to a packetloss, and an operation with respect to the packet loss is recorded in anapplication. According to a document that is a basis for a transmissionmethod using an RTP such as Request For Comments (RFC) 3550, an initialvalue of a sequence number needs to be arbitrarily determined for plaintext attacks that are well known in more difficult encryption. The MMTsystem may detect a lost MAU by using a sequence number, although notguaranteeing safety of transmission.

A field regarding a timestamp indicates a particular time in which datais generated or changed.

A field regarding an MAU's indicator includes an indicator for atransmission service. For example, the field may include a serviceprotection indicator and an application layer FEC indicator as a flag.When the MAU indicator is indicated using 2 bits, (00) indicates serviceprotection, (01) indicates an application layer FEC, and (10) and (11)may be used to indicate different contents.

FIG. 4 is a flowchart for constructing a payload of a multimedia framecorresponding to a multi-service/content and transmitting the payload ofthe multimedia frame over a heterogeneous network in an MMT systemaccording to an embodiment of the present disclosure.

Particularly, FIG. 4 shows an operation performed in the MMT D.1 layer332 of the Layer D 330 among the layers illustrated in FIG. 3.

Referring to FIG. 4, to transmit multimedia data, the ME is divided intoa plurality of blocks at operation 400. The MMT payload of the MAU isconstructed using the divided blocks, and the MMT payload may includeany one block or a fragment of any one block or the plurality of blocksat operation 410. Once the MMT payload is constructed, the MAU header isconstructed by including information regarding data included in the MMTpayload or MMT payload information related to the service protectionindicator or the application layer FEC at operation 420. Once the MAUheader and the MMT payload are constructed, the MAU header and the MMTpayload are combined to construct a payload of the frame at operation430. The payload of the constructed frame is combined with the header ofthe frame for transmission in one frame.

While the present disclosure has been shown and described with referenceto various embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present disclosure asdefined by the appended claims and their equivalents.

What is claimed is:
 1. An apparatus for receiving media data in abroadcasting system, the apparatus comprising: a receiver configured toreceive a packet including a packet header and a packet payload of mediadata; and a controller configured to extract the packet payload, whereinthe packet payload comprises: a data unit generated from the media data,a fragmentation indicator indicating information about fragmentation ofthe data unit in the packet payload, length information on the packetpayload, aggregation information on whether the data unit is aggregatedwith another data unit, and sequence number information on the dataunit, wherein, if the data unit is fragmented, the packet payloadcomprises a fragmented data unit and the fragmentation indicatorindicates information which part of the data unit is included in thepacket payload, and wherein, if the data unit is not fragmented, thepacket payload comprises at least one complete data unit and thefragmentation indicator indicates that the packet payload includes theat least one complete data unit.
 2. The apparatus of claim 1, wherein ifthe data unit is fragmented, the information of the part of the dataunit is one of a first fragment, a last fragment, and other fragmentthan the first and the last fragment.